How many sentients are enough?

In a situation of human immortality, reached as humans include increasing amounts of artificial processing together with their biological processing, machines become more intelligent and humans upload to machines or other substrates, a question naturally arises - how many humans or consciousnesses (consciousni?) or sentients are optimum in the world or universe?

One view says as many as possible, or that can be appropriately sustained given resource constraints. Another view says the same amount as we have now. Another says fewer, since a variety of operations may now be sustained with machines. In the possible event of little resource constraint, should "parents," begetters of new consciousnesses, via cloning, original mixing, and other traditional and novel methods, either be limited or incented to have or create as many new consciousnesses as is their whim?

A deeper perspective of the problem naturally asks what are sentients doing? What is their purpose, use? The obvious reason for consciousness is to extend knowledge, information, ideas, innovation and discovery. Maybe different types of consciousness are possible, leading to new ways of cross-consciousness collaboration. Ignoring the jaggedness between current consciousnesses and steps to educate, entice and realize the transition to immortality, the presumed conclusion is the American school of consciousness creation, that more, more, more is better.